This invention relates to a fluid separation apparatus, and more specifically, to such an apparatus which includes an easily replaceable and disposable fluid separation module capable of engaging, and being retained in fluid tight relationship, with a mating connection device.
Fluid separation devices of the types described above have been used to control contamination in industrial processes for many years. Such devices are an integral part of the manufacture of many products including pharmaceuticals, food stuffs and beverages. However, nowhere is the need for effective contamination control greater than in the semiconductor fabrication industry. With circuit details in the submicron range and with further feature size reductions inevitable, the need for control of particulate, ionic, organic and other contaminants in semiconductor process fluids is essential. Also, because semiconductor devices are fabricated in clean rooms, it is important to minimize the potential of contaminating the manufacturing environment. For this reason disposable fluid separation devices are preferable in semiconductor fabrication processes in order to minimize contamination of the process lines as well as the clean room.
Examples of semiconductor process fluids which are processed at the point of use (POU) include those chemicals used in photolithographic processing (photochemicals). Photochemicals include materials such as primers, adhesion promoters, photoresists, edge bead removers, antireflective coatings, developers, dielectrics, and the like. Such chemicals are commonly dispensed onto the silicon wafer by a specialized pump and subsequently dispersed into a uniform thin film using a process called spin coating, and the purity of these chemicals at the POU is essential to producing acceptable product yields.
Fluid separation devices are in general of two types. In the first type, the separation element is a replaceable component, while the pressure vessel which houses the element, i.e. the housing, is reusable. The housing also contains appropriate fluid connections to the rest of the fluid processing system. Replacing the fluid separation element requires opening the housing, removing the separation element, installing the replacement separation element into the housing and closing the housing. There are many disadvantages to this type of fluid separation device. First, the replacement operation is time consuming, especially if access to the housing is restricted. Secondly, because the housing contains a quantity of the fluid being processed and because the fluid separation element is usually saturated with the fluid, spillage of the fluid usually occurs. In the case of hazardous fluids, spills can be a threat to the well-being of personnel in the area as well as potentially damaging to nearby equipment and facilities. Finally, the opening of the housing exposes the internal surfaces of the fluid processing system to unwanted contamination from the surrounding environment.
The second type of separation device is one in which the separation element is permanently attached to the housing, which also contains appropriate fluid connections to the rest of the fluid processing system, to form an integrated module. In this case, replacement involves disconnecting the entire separation module from the fluid processing system and reconnecting a replacement module to the system. In this manner replacement is easier, exposure of the operator to hazardous chemicals is minimized, the reliability of the connection is significantly improved, and contamination of the fluid processing system by the environment is reduced. This type of separation device is called a disposable module, since the whole module is removed and disposed of whenever the separation element requires replacement.
Different types of disposable separation modules are used in industrial applications. So called `in-line` disposable modules have feed and effluent connections disposed at opposite ends of the housing. While there are virtues to this module configuration, they are obtained at the expense of several disadvantages. First, they are prone to fluid loss when the module is disconnected from the fluid processing system and special efforts are required to minimize leakage of fluid from the module and subsequent spillage on the equipment to which the module is connected. Secondly, fluid systems designed to accept in-line modules are more complicated due to the need for having two sets of fluid connections, one at the inlet end and another at the outlet end of the module, and thus are not readily adaptable for use with quick connect assemblies.
Another type of disposable module has all of the connections on one end of the housing with the feed and permeate connectors typically perpendicular to the body of the housing and opposed to each other thereby giving the module the shape of a "T". Such modules are therefore called "T-line" modules. T-line modules solve many of the problems associated with in-line modules. In particular, they prevent or reduce fluid loss during replacement if the end with the connections is on top, and the fluid processing system is simpler by virtue of having all fluid connections grouped in one location. However, T-line modules produce a dead-space, or non-swept volume of liquid, between the bottom of the separation element and the housing, which is undesirable.
Each of the types of disposable modules described above still require that each connection to the fluid processing system be individually made. A fluid connection requires two mating connectors, typically a male and female connector, and three separate actions to accomplish the connection, namely alignment of the bodies of the two mating connectors, engagement of the body of the male connector into the female connector to produce a fluid tight seal, and retention of the relative position of the two connectors to maintain the fluid tight seal under processing conditions. The design of mating connectors must thus include the ability to produce a fluid tight seal and some mechanism to retain the connectors in this arrangement.
The class of connectors commonly used have connector bodies that are circular in cross section, the body of the male connector being in the shape of a cylindrical rod, while that of the female connector being in the shape of a cylindrical well. The dimensions of the two connectors are such that, once engaged, they sealingly mate, i.e. fluid can flow from one connector to the other without any fluid loss, the sealing occurring at a single circular boundary between the mating connectors. Retention of the mating connectors in fluid tight engagement is accomplished by means of threaded fasteners (e.g. screw and nut pairs). This class of connectors produce a reliable seal by virtue of their simplicity in which only circular surfaces are used, and by the fact that each connection is exclusive of one another, i.e. no two connections share connector bodies or sealing boundaries/surfaces.
Regardless of what connector design is employed, disposable modules usually require that multiple connections be made sequentially, a minimum of two connections, and more typically three or four. Moreover, threaded fasteners are cumbersome and sometimes difficult to engage, factors which involve the subsequent consumption of additional time and effort. Furthermore, the module has to be held in place while the connections are being made, which makes the connection event even more difficult since it requires performing two actions at the same time (i.e., holding the module in place and attaching each connector sequentially). Finally, in those applications in which the permanent connections to the fluid processing system are not rigid, as for example when flexible tubing is used, liquid has a tendency to be discharged as the connections disengage. All of these problems exacerbate the time and effort required to replace a disposable module, in addition to still allowing for exposure of personnel to hazardous materials, and contamination of the manufacturing environment.
For these reasons, some disposable separation modules have been designed with features that allow them to be connected quickly and easily to the fluid processing system in a "quick-connect" fashion. These types of quick-connect modules provide for a set of connectors that sealingly engage with a single, simple stroke or action, to a mating set of connectors attached to a reusable substrate. Different types of mechanisms have been designed to accomplish quick-connect retention, all of which heretofore have required some form of relative motion between the male connector and its female counterpart, most commonly a twisting action.
Thomsen et al., in U.S. Pat. No. 4,654,142 describe a filtering system for water treatment which discloses the use of a separate and reusable head with connecting ports that sealingly mate to connecting ports on a disposable water purification cartridge. To facilitate the replacement of the disposable module, the two connecting ports are located on the same end of the disposable module, and are disposed to seal coaxially. A bayonet-type locking device is also attached to the module to retain it to the reusable head. The two ports as well as the locking device couple to a mating head to secure the module in a fluid tight fashion during use.
In another example, Groezinger et al., in U.S. Pat. No. 4,719,023, disclose a similar module and mounting device, describing the module as a "twist on disposable filter". According to this disclosure, the module and mounting device are connected by first aligning the bayonet lugs of the module with the appropriate bayonet recesses in the mounting device, axially inserting the module connector into the bore of the mounting device, then rotating the module about its longitudinal axis to engage the bayonet lugs and thereby retain the disposable filter.
While these quick-connect mechanisms address the convenience-of-use aspect of disposable fluid separation modules, they suffer from several deficiencies. First, the connectors share a common seal between the fluid inlet and outlet ports which is undesirable since a leak on the shared seal of the feed port would lead to contamination of the permeate stream with unpurified feed stream; furthermore, this contamination would go undetected. Secondly, the act of rotating the fluid separation module relative to the mounting device to lock together the two components inevitably generates particles as the sealing surfaces move relative to each other, thereby contaminating the fluid passages and ultimately the fluid being purified. Finally, these modules require that the connecting ports be grouped about the axis of rotation of the module which may compromise the liquid flow pattern and further complicate and constrain the fabrication of the module's housing and connector ports. Accordingly, it would be desirable to provide a fluid separation module of the quick-connect type that utilizes reliable fluid connections, and a retention mechanism which does not require relative motion between one connector and its mating counterpart.